Table 1.

Demographic features of patients with amyotrophic lateral sclerosis in the study

Variables	Total
n	1587
Sex ratio (male/female)	1.4 (922/665)
Sporadic/familial	1523/64
Definite/probable	1094/493
Mean age at onset (years), mean±SD	53.9±11.7
Age at onset (<20/21–30/31–40/41–50/51–60/61–70/>70)	4/32/170/392/435/435/119
Mean disease duration at registration (months), mean±SD	16.4±12.5
Site of onset (spinal/bulbar)	1237/350
Survival status (alive/died/lost to follow-up)	479/982/126
Median survival time (95% CI)	40.9 (38.7 to 43.1)